No, 30 cm is not really "pretty much" extension.
The 6.5 Gator will probably rig OK on a 460 mast, but you won't get the full performance and tuning range because the 460 cm IMCS 24-26 mast will be too stiff for a sail designed for a 430 cm IMCS 21-23 mast.
The top of the sail will not "twist off" correctly as the mast won't bend enough under the same amount of downhaul.
Many sails use up to 38-40 cm of extension to achieve the correct luff length and bend characteristics deemed necessary in the design of the sail.
Most tall mast bases are in the 42-45 cm range at the top (longest) setting so 30 cm is certainly not "over extended".
I've seen a few carbon extensions snap off at the adjustment rings, but if you use a good quality alminum mast base you should have no problems at all.
It may be that the designers used the 430 Blue Line RDM in the 6.5 '07 Gator. The '08 Gator recommends a 460 cm Blue Line SDM. which may be a change from the '07 design.
Hope this helps,
Last edited by Roger; 8th February 2008 at 10:57 PM.